Set torque wrench



De@ 19 1944- H. P. MORRIS 2,365,486

SET TORQUE WRENCH Filed Aug. 1'?, 1942 IN VN TOR.

H/i/e/eYRMmK/J,

BY uw Mr-ry.

Patented Dec. 19, 1944 UNITED STATES PATENT OFFICE SET TORQUE WRENCHHarry P. Morris, Coronado, Calif.

-ApplicationAugust 417, 1942, Serial No. 455,095 2 claims. l(icl. :s1-53) This invention relates'to a-Wrench and particularly pertains to aset torque Wrench.

In various mechanical assembling-operations, and particularly inAordnance and aircraft Work it is necessary to tighten bolts and nutsrapidly and at the same time to linsure Athat the parts have beenscrewed togetherto produce a desired holding action without applying anexcessive degree of torque Avvhichwvould tend to weaken or fracture thethreads of the parts being tightened. Various devices have been providedto foperatein connection with Wrencheswhereby the degree `of torqueapplied bythe Wrench is indicated either audibly or visibly. Devices ofthis character `tend to increase the co-"ordination` and efliciency ofthe operator andit has beeniound desirable to pro'- vide meansWhich'will indicateautomatically on the Wrench when thejselected amountof torque has been app1ied, this indication being imparted to the handlegrip of the Wrench so that the operator Will be sensible ofthe`indication Without observing dials, needle,` or other indicatingmembers. It isalso'desirable'to provide a'wrench which may beset toa'desired tensionsotha'tthe Wrench cannot exert -a pressuregreatervthana predetermined sei-,pressure and so'that this maxi# mum setpressure may be indicated to the operator. 1

It is the principal object of the lpresent inven-` tion therefore to'provide a torque Wrench tted with simple and effective means wherebythe Wrench may `be set to a predetermined maximum torque and will'thereafter function to operate upon threaded members to be tightened-tothat maximum torque only, and to indicate when the maximumtorquehas beenreached.

.sembled Wrench with the cover'removed and the parts in a normal'position; i

Fig, 2 is a view in plan showing` the wrench with its cover removed andthe parts insa maximum torqueposition'.v

Fig. `3 is avewin central 'longitudinal' 'section Fig. 2 and showsfthedetailsofconstruction of the Wrench.

Fig. 4 Vis a fragmentary `view :showingtheapplication of ademountablehead.

Fig. 5 is a fragmentary View in= elevationishowing the end 4portion of'the handle and the .micrometer calibrations.

Referring `more particularly to the drawing, .i0 indicates a Wrenchlbody at one end ot Whicnisa hand grip Il. The Wrench' body is preferablymadefof steel andincludes a caseItZ.` The case l 2 is formed With-a Wallalongitsperimeter. One end of the case has -a substantiallysemi-circular wall portion f|"3 and oppositeside Wall portions M andl5.4 4The side Wall portions taperwtoward each other and terminate in anendportion 1'6. 'Formed integral with the end portion 116 i's a tubularhandle ll'l. The tubular handle .has `a central bore ITB vinternallythreaded at its outer end as indicated 'at I9 and communicating with abore 20?` `of -reduced diameter Whichlextends throughthe portion i6 andfinto -thefcavity 21 formed by the walls -alongtheiperimeter 'of thecase. The handle 4Il `and'theboresfll and Zilf'are 'in longitudinalalignment -and are centrally aligned 'with thelongitudinal -aXis `ofvthe cavity A2l in the case.' The wall portion .I3 which is iat the'opposite end of the' case from the bore 2D represents an arcuate lengthgreater Vthan..180 for a purpose to be Ahereinafter described. The *casel2 has alcor2'2 onone side `thereof and is provided withia cover plate23 on the opposite 'side thereof. The .floor andthe cover plate are.ormedaat fone end :with relatively .large `complementary openings A211and.25 respectively, which openings are in axial alignment, the axisintersecting the longtudinalcenterfof thecase andbeing at right anglesthereto. Formed through the end'ofthe arcuate Wallsection -l3isanelon'gated slot'or opening 26, the median line of Whichis coincidentlWith the longitudinalcenter line of the case. A similargopeningl-lYisiforrned to the side -of thecase and Withitsmedian line substantiallyat -rightangles to that of theopeningZB, both o'f said median linesbeing.. radially -disposed with relation to the axis' of the openings"211 l"and 25. Mounted Within the openings 24 arrd2`5 is a rot-ary head28. ThislheadA is formedwithoppol 'assembled body :structure l0.Intermediate the cylindrical portions 1291 and 3U is a substantially'cylindrical lportion 3l of` larger `diameterlwhiclr.l is

of a thickness representingthe space between the inner faces of thefloor 22 and the plate 23 respectively. This prevents the rotating head28 from becoming displaced, At one side of the rotating head 28 andformed integral with the cylindrical portion 3I are lugs 32 and 33between which a radial seat 34 is formed. This seat extends in thegeneral direction of the longitudinal axis of the body structure III andtoward the handle II. Mounted within the cavity 2l is a lever 35 and alink 36. The lever 35 is secured upon a pivot pin 31 which extendsthrough the cover plate 23 and is threaded into the floor 22 the axis ofthe pin being parallel to the ro-tating axis of the head 28 and lying ina plane in the longitudinal center of the body I. At lone end of thelever 35 is a finger 38 which extends into the seat 34 on the rotatinghead 23. The end of the finger is rounded so that as the head 28 rotatesthe finger may swing around the axis 31 without binding. The oppositeend of the lever 35 is formed with an extension 39 of reduced thickness.This extension projects into the forked end of the link 36. A connectingpin 40 extends through the forked end of the link 36 and the extension39 yof the lever 35 to connect the lever and the link pivotally. Theopposite end of the link 36 is similarly constructed and receives anextension 4I of a piston rod 42. The rod 42 reciprocates within the*bore 26 of the body of the structure and is pivoted to the link 36 by apin 43. The end of the rod 42 opposite the extension 4I has an enlargedcollar 44 which ts within the bore I8 of the handle and limits themovement Vof the rod 42 through the bore 26. A pin 45 extendslongitudinally of the end of the rod 42 and into the bore I8. Positionedwithin the bore I8 is a helical tension spring 46 which rests againstthe end of the piston rod 42 at one end and against a plug 41 at theopposite end. The plug 41 is tted with a pin 48. The pins 45 and 48extend into the opposite ends of the spring 46 and center it. The plug41 is formed at its outer end with a concaved ball seat 48 to receive aball 49. The plug extends into a threaded adjusting cap 56 which isthreaded into the bore I9 of the `handle II. A concaved seat 5I isformed within the bore adjusting cap and between the seats 48' and 5I aball 49 is held. The cap 50 projects beyond theend of the tubular handleII and is fitted with a squared head 52 by which the cap may be rotated.

For purposes to be hereinafter set forth a stop screw 53 is threadedthrough the side wall I5 of the body I of the wrench and limits theswinging movement of the lever 35 as shown in Fig. 2 of the drawing. Therotary head 28 of the wrench is provided with a central opening 54 whichis here shown as being square. This opening is to accommodate the headof a nut or bolt. It is to be understood that the opening may be of anydesired or necessary configuration. Formed through the side wall of therotary head are slots 55 and 56. These slots are in the plane of theslots 26 and 21 of the, body of the wrench 'and may receive the shank 51of interchangeable wrench heads 58.

In order to properly adjust the tension of the spring 46 suitablegraduations 59 are formed around the circumferential end face of thehandle II and cooperate with a pointer mark 60 upon the cap 50. Formedthrough the side walls of the handle II are slotted openings 6I. A pin62 extends through these openings and the plunger 41.

Graduations 63 are made upon the body of the handle II along the slottedopenings 6I so that an index groove 64 in the end o f the pin 62 may bebrought to register therewith and will indicate spring tension imposedupon the spring 46 by the cap 56. f

In operation of the present invention the wrench is assembled as shownin the drawing, after which the adjusting cap 56 is tightened until theindex mark 60 is brought to register with the graduations 59representing the number of inch pounds of torque. This also forces theplunger 41 down so that the graduation rmark 64 on the pin 62 willregister with the graduation 63 disposed along the slot 6I in thehandle. This will indicate the number of hundred inch pounds torqueadjustment which have been made. Thus the registration of the index mark66 with a particular calibration 59 will indicate the maximum number ofinch pounds to which the wrench is to be pressed. The wrench is thenapplied to the element which is to be turned and the torque force isdelivered in the direction of the arrow a as indicated in both Figs. land 2. In the normal position of the wrench parts as shown in Fig. l ofthe drawing, the head 28 is disposed so that its radial seat 34 will beat an angle to the longitudinal center of the wrench in the direction ofthe application of torque, and that the lever 35 will be disposedangularly of the longitudinal center of the wrench oppositely from thatof the radial seat. It will also be noted that link 36 is disposed 'offcenter to connect the piston rod 42 and the free end of the lever 35. Solong as the member seated within the rotary head 28 and to be rotateddoes rotater all of the parts of the wrench will remain in the positionshown in Fig. l, since the response to torque force will be less thanthat required to compress the spring 46.

When, however, the rotated part, such for example as the nut, is screwedon to the threads of a complementary member to a point where the partsare sufficiently tightened to resist the torque force applied by thewrench, the rotating head 28 will tend to stand stationary and thewrench will swing around the axis of the rotating head, with the resultthat the lever 35 will swing around the fulcrum pin 31 and cause thelink 36 to tend to swing to a position of longitudinal alignment withthe lever. It will be recognized that the lever and the link have atoggle joint action with relation to each other, and as they strain theywill force the piston rod 42 longitudinallyl against the action of thespring 46 and thus will cause a condition of lost motion in theapplication of torque force by the handle. This will continue until thefree end of the lever arm 35 strikes the stop screw 53. It will thus beevident that by this arrangement it will be possible for the operator ofthe wrench to be advised instantly when a torque force is applied to thewrench which is resisted by the element which is engaged and is beingtightened by the rotary head 28. It is to be understood that whendesired an interchange of removable heads 58 may be made, asshown inFig. 4 of the drawing. It willalso'be recognized that by the use of thestructure here disclosed the tension of the spring 46 may be instantlychanged to produce any set amount of torque, and that the mechanism isrugged and strong and cannot be easily broken, even though the operatordoes not heed the warning signal produced by the movement of the togglejointin the wrench when a maximumset torque has been reached.

While I haveshown the preferredform of invention as now known to me, itis to be understood that various changes may be made in the combination,construction, and arrangement of parts by those skilled in the art,without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

l. A set torque wrench, comprising a housing having a cavity at one endthereof and being formed with a cylindrical handle at the opposite endthereof disposed in longitudinal alignment with the cavity, said cavitybeing closed at opposite sides by flat parallel wall sections spacedfrom each other and through which aligned annular openings occur, aWrench head disposed between said walls and having cylindrical bossesextending oppositely and outwardly through said openings to rotaterelative thereto, said head being formed with a central passageway of aclonguration to receive an object to be rotated, a pair of spaced radiallugs projecting from the side face of the head within -the cavity andforming an intermediate seat normally disposed in the plane of thelongitudinal axis of the wrench structure, a lever pvotecl between saidside wall sections upon an axis normal to the longitudinal axis of theWrench and lying along the plane of the center line of the wrench` saidlever being formed at one end with an operating ringer extending intothe seat, a link pivotally connected to the opposite end of said lever,whereby the link and lever will form a toggle joint, a pressure rodlongitudinally slidable within the handle of the wrench and pivotallyconnected to the link, 1a, compression spring mounted within the handleand bearing against the end of the pressure rod, a plug resting upon theouter end of said spring, and an adjustable cap threaded into the end ofthe handle, whereby thetension upon the spring may be varied, saidtoggle structure being normally held with its elements in angularrelation to each other by compression of said spring to hold the wrenchhead with its lugs and seat disposed at an angle to the longitudinalcenter of the wrench, whereby a torque force exerted against the handleof a magnitude greater than the set compression of the spring will tendto straighten the toggle and permit relative rotation of the wrench bodyand handle with relation to the wrench head.

2,. The structure of claim 1 including an adjustable stop against whichthe toggle structure may swing to limit the relative rotation of theWrench body and its head.

HARRY P. MORRIS.

